Spokes for integrally coupling a rim and a hub by applying tension between an annular rim for mounting a tire of a conventional general bicycle and a hub into which a wheel shaft is inserted are threadedly fitted in a nipple with external threads provided on one end thereof, are engaged with spoke holes of the annular rim by the nipple, one end thereof having its extreme end bent into a J-shape and inserted into spoke insert holes opened to a collar portion (hereinafter referred to as “hub collar”), a large diameter portion of the extreme end of the end being engaged with and stopped at the collar portion. Incidentally, the portion bent into the J-shape of the spokes is quickly deteriorated due to fatigue, thus shortening the service life of the spokes. Further, the fact that the hub collar surface is not formed in parallel with the elevation angle formed by the spokes stretched between the rim and the hub results in one of causes of shortening the service life of the spokes because a load is applied to the J-shaped portion of the spokes.
There has been known an arrangement wherein a spoke support shaft is inserted into a flange provided on a hub, a spoke insert hole for engaging one end of the spoke as a large diameter portion is provided in the spoke support shaft, and the spoke insert hole is made to be larger than axial diameter of the spoke so that the spoke is tiltable freely at an angle within a fixed range, whereby the other end of the spoke is threadedly engaged, in a linear state, with the nipple of the rim. However, in the above-described proposal, it is merely that the spoke insert hole of the spoke support shaft is larger than the diameter of the spoke as described above and is slightly smaller in diameter than the large diameter portion of the spoke end, and therefore, durability is not sufficient due to the force applied to the spokes so that the spokes tend to be slipped out.
Further, as spokes, aerospokes whose section is flattened in order to reduce air resistance during traveling are sometimes used. However, in case of such aerospokes having the section flattened as mentioned above, since the aerospokes cannot be inserted into normal spoke holes having a diameter of about 2 mm opened to the hub, it is necessary that a slit having a width of 1 to 2 mm is provided in the hub to form a spoke collar. Therefore, since the spoke collar is in contact with the slit, it cannot endure against the tension applied to the spokes, and is sometimes slipped out.
Furthermore, an open portion is provided in the spoke hole of the hub for inserting and mounting the aerospoke into the hub. However, since the open portion causes strength of the spoke hole to lower, it is necessary to make the circumference of the spoke hole thicker, which results in a defect of increasing weight of the hub.
According to the conventional rim, in a ratio between rim width and rim height, the rim width had a value larger than the rim height. However, recently, the air resistance of a bicycle has been discussed, and a rim having larger rim height has been developed. However, this rim has been used under the circumstances the number of spoke holes is the same as the conventional rim in which the number of spoke holes is 32 or 36. On the other hand, the fact that the rim height is large results in increasing the longitudinal rim strength in a centrifugal direction by about two times as compared with the conventional rim.
The fact that in the rim of high longitudinal rim strength, there are many spokes enables to supply a wheel without vibration even if spokes to which tension is not applied should present in spokes. That is, this means that even if the spoke tension is made somewhat uneven, wheels without vibration can be supplied. However, at present, the wheel without vibration as described produces vibration during the use to create trouble.